A typical wireless communication device, such as a mobile phone, comprises, among other things, a processor coupled to a memory and to a transceiver, each enclosed in a housing. A mobile power source, such as a battery, is coupled to and supplies power to the processor, the memory and the transceiver. A speaker and a microphone are also enclosed within the housing for transmitting and receiving, respectively, acoustic signals to and from a user of the wireless communication device. The wireless communication device communicates information by transmitting and receiving electromagnetic (“EM”) energy in the radio frequency (“RF”) band via an antenna coupled to the transceiver.
During transmission, the source signal is modulated, amplified and transmitted via the antenna. Conventional wireless communication devices include a power amplifier that has a fixed gain for amplifying the modulated signal prior to transmission. The simplicity of such an implementation, however, is achieved at the cost of reduced signal-to-noise ratio (“SNR”), particularly during low power operation. For example, in order to operate the wireless device at low power while maintaining a relatively fixed power amplification, the source signal may need to be significantly attenuated, resulting in reduced signal levels and, ultimately, in reduced SNR. Reduced SNR significantly diminishes the performance of the wireless communication device. This problem is even more pronounced for mobile handsets, such as CDMA mobile handsets, which operate in low power for a substantial amount of the time.